Different processes lead to similar patterns: a test of codivergence and the role of sea level and climate changes in shaping a southern temperate freshwater assemblage

Abstract

BackgroundUnderstanding how freshwater assemblages have been formed and maintained is a fundamental goal in evolutionary and ecological disciplines. Here we use a historical approach to test the hypothesis of codivergence in three clades of the Chilean freshwater species assemblage. Molecular studies of freshwater crabs (Aegla: Aeglidae: Anomura) and catfish (Trichomycterus arealatus: Trichomycteridae: Teleostei) exhibited similar levels of genetic divergences of mitochondrial lineages between species of crabs and phylogroups of the catfish, suggesting a shared evolutionary history among the three clades in this species assemblage.ResultsA phylogeny was constructed for Trichomycterus areolatus under the following best-fit molecular models of evolution GTR + I + R, HKY + I, and HKY for cytochrome b, growth hormone, and rag 1 respectively. A GTR + I + R model provided the best fit for both 28S and mitochondrial loci and was used to construct both Aegla phylogenies. Three different diversification models were observed and the three groups arose during different time periods, from 2.25 to 5.05 million years ago (Ma). Cladogenesis within Trichomycterus areolatus was initiated roughly 2.25 Ma (Late Pliocene - Early Pleistocene) some 1.7 - 2.8 million years after the basal divergences observed in both Aegla clades. These results reject the hypothesis of codivergence.ConclusionsThe similar genetic distances between terminal sister-lineages observed in these select taxa from the freshwater Chilean species assemblage were formed by different processes occurring over the last ~5.0 Ma. Dramatic changes in historic sea levels documented in the region appear to have independently shaped the evolutionary history of each group. Our study illustrates the important role that history plays in shaping a species assemblage and argues against assuming similar patterns equal a shared evolutionary history.

Evolutionary Drivers of Diversification and Distribution of a Southern Temperate Stream Fish Assemblage: Testing the Role of Historical Isolation and Spatial Range Expansion

“…Studies have cited a plethora of processes, such as global sea-level changes, climatic oscillations, orogenic events, river capture and ecological gradients as the major drivers of diversification and geographical distribution of many freshwater assemblages [5]–[16]. One challenge, particularly in understudied regions, is identifying which of these processes played a major role in shaping patterns of regional diversity.…”

“…One challenge, particularly in understudied regions, is identifying which of these processes played a major role in shaping patterns of regional diversity. Integrating data from multiple co-distributed taxa provides a more powerful approach for investigating the evolutionary and biogeographical effects of both historical events and the environmental characteristics of a region [15], [16]. The present study uses comparative phylogeographic and biogeographic approaches to examine the evolutionary drivers of diversification and the processes that gave rise to extant geographical distributions of co-distributed stream fishes from the south-western Cape Floristic Region (CFR) of South Africa.…”

Genetic and phenotypic variation among Galaxias maculatus populations reflects contrasting landscape effects between northern and southern Patagonia

“…The combined impact of these processes on current biodiversity patterns is beginning to be understood (Ruzzante & Rabassa, 2011) for terrestrial (e.g. Ruzzante et al, 2008;Unmack et al, 2009;Barber et al, 2011;Zemlak et al, 2011). Ruzzante et al, 2008;Unmack et al, 2009;Barber et al, 2011;Zemlak et al, 2011).…”

Population genetic structure of the freshwater anomuran Aegla uruguayana Schmitt, 1942 (Decapoda, Aeglidae) in the central region of Argentina

“…In freshwater decapods, population genetic evidence studies suggest different patterns that indicate structural levels according to distance or population separa tion in time or space, or variations according to habitat area, habitat age, and the immigration potential of the locality (Fuller & Lester, 1980;Daniels et ah, 1999;Daniels, 2003;Schubart & Huber, 2006;Shih et al, 2006;Xu et al, 2009;Klinbunga et al, 2010;Barber et al, 2011Barber et al, , 2012.…”

“…Aeglids population variability by molecular or genetic evidence is scarce (D'Amato & Corach, 1997a, b;Santos et al" 2009;Xu et a l, 2009;Barber et al, 2011Barber et al, , 2012. Here, we applied the Inter Simple Sequence Repeat (ISSR) marker, which is a relatively recent technique (Bomet & Branchard, 2001), to evaluate variation in microsatellite regions.…”